HTML Code

<!DOCTYPE html>
<html lang=en>
<head>
  <meta charset=UTF-8>
  <meta name=viewport content="width=device-width,initial-scale=1">
  <title>id — dynamic JS</title>
  <style>body{font-family:system-ui,sans-serif;margin:0;padding:1.5rem;background:#f8fafc;color:#334155;line-height:1.7}h1{margin:0 0 1rem;font-size:1.25rem;color:#0f172a}#dynamic-element,#new-dynamic-id{max-width:420px;padding:.85rem 1rem;background:#fff;border:1px solid #e2e8f0;border-radius:8px;font-size:.875rem}#new-dynamic-id{border-left:4px solid #8b5cf6}button{display:block;margin-top:.75rem;font:inherit;padding:.45rem .85rem;border:1px solid #cbd5e1;border-radius:6px;background:#2563eb;color:#fff;cursor:pointer}.status{margin-top:.75rem;font-size:.8125rem;color:#64748b;max-width:420px}code{background:#e2e8f0;padding:.1rem .35rem;border-radius:4px}</style>
</head>
<body>
  <h1>id — dynamic JS</h1>
  <div id=dynamic-element>Current id: <code>dynamic-element</code></div>
  <button type=button id=changeIdBtn>Change id to new-dynamic-id</button>
  <p class=status id=status>Click the button to update the element id.</p>

  <script>document.getElementById("changeIdBtn").addEventListener("click",(function(){var e=document.getElementById("dynamic-element");e.id="new-dynamic-id",e.innerHTML="Updated id: <code>new-dynamic-id</code>",document.getElementById("status").textContent="getElementById now uses the new id value."}))</script>
</body>
</html>

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HTML id Attribute — Dynamic id with JavaScript